JP6398325B2 - Water heater - Google Patents

Description

  The present invention relates to a hot water supply apparatus, and more particularly to a hot water supply apparatus having a function of determining scale clogging caused by scale accumulation in a heat transfer tube of a heat exchanger.

  Conventionally, various hot water supply apparatuses according to heat sources such as a gas hot water supply apparatus, an electric hot water supply apparatus, and an oil hot water supply apparatus have been widely used in general households. In particular, a gas hot water supply device exchanges heat between a blower fan that takes in combustion air from the outside, a burner unit that mixes and burns combustion air and fuel gas, and high-temperature combustion gas and water flowing through a heat transfer tube. A heat exchanger for heating the water, an exhaust pipe for discharging the exhaust gas after the heat exchange to the outside.

  As the heat exchanger, generally, a heat transfer tube and a fin-and-tube heat exchanger composed of a plurality of fins fixed to the heat transfer tube so as to be able to transfer heat are applied. In general, the heat transfer tubes and fins made of copper material are widely used.

  By the way, when using tap water with high hardness with respect to the tap water supplied to the heat exchanger, calcium ions, magnesium, etc. contained in the tap water are combined with carbonate ions, sulfate ions, etc. A scale is formed, and this scale accumulates in the heat transfer tube of the heat exchanger, causing clogging of the scale, resulting in a problem that heat exchange efficiency in the heat exchanger is deteriorated. Moreover, when a hot-water supply apparatus is used for a long time, a sticking will adhere to the fin of a heat exchanger, a fin clogging will generate | occur | produce and there also exists a problem that the heat exchange efficiency in a heat exchanger deteriorates.

  Continuing to use the hot water supply device with the above scale clogging or fin clogging may damage the heat exchanger.If an abnormality such as clogging of the scale or clogging of fins occurs, remove the scale or It is necessary to perform maintenance for removal. For this reason, conventionally, the hot water supply apparatus has been provided with a function of detecting an abnormality such as scale clogging.

  For example, in the apparatuses described in Patent Documents 1 to 3, a technique for determining scale clogging or the like based on a rise in the temperature of hot water due to post-boiling after stopping combustion is disclosed. Further, in the hot water heater described in Patent Document 4, when it is detected that the heat exchange efficiency has decreased during the combustion operation, the amount of combustion is forcibly reduced, and the subsequent heat exchange efficiency and the reference efficiency are compared. Thus, a technique for determining whether the cause of deterioration in heat exchange efficiency is clogging of scales or clogging of fins is disclosed.

Japanese Patent No. 4854020 JP 2003-254615 A JP 2013-160488 A JP 2008-215657 A

  However, as in the devices of Patent Documents 1 to 3, when an abnormality is determined based on the temperature rise of hot water due to post-boiling after stopping combustion, it is due to heat transfer failure due to scale clogging or heat transfer failure due to fin clogging. The cause of the deterioration of the heat exchange efficiency cannot be accurately determined, and there is a possibility that troubles such as troublesome work may occur when performing maintenance and countermeasures. In addition, if the amount of combustion immediately before the stop of combustion is low, or if instant hot water is being executed, there is a problem that the rise in hot water temperature due to post-boiling cannot be used for abnormality determination.

  Therefore, in the hot water heater of Patent Document 4, determination is made to identify the cause of scale clogging or fin clogging during the combustion operation. However, in the technique of Patent Document 4, the cause is identified during the combustion operation. Therefore, since the amount of combustion is forcibly reduced even in a normal hot water supply operation state, there arises a problem that the amount of hot water supply and the hot water supply temperature fluctuate unintentionally by the user.

  An object of the present invention is to provide a hot water supply apparatus that can reliably determine scale clogging by a simple method.

The hot water supply apparatus according to claim 1 is a hot water supply apparatus including a fin-and-tube heat exchanger for heating clean water with combustion gas and a heat exchanger can body for housing the heat exchanger. A temperature detector for detecting the surface temperature of the heat exchanger can body, and a scale is deposited in the heat transfer tube of the heat exchanger when the detected temperature detected by the temperature detector exceeds a set temperature. The temperature detection means is located immediately above the combustion section that always burns during hot water supply operation and in the vicinity of the downstream side of the heat transfer tube closest to the combustion section of the heat exchanger. It is provided on the surface of the heat exchanger can body .

  According to the first aspect of the present invention, the hot water supply apparatus includes a temperature detecting means for detecting the surface temperature of the heat exchanger can body, and a case where the detected temperature detected by the temperature detecting means is equal to or higher than the set temperature. Judgment means that determines that scale has accumulated in the heat exchanger tubes of the heat exchanger, so if the surface temperature of the heat exchanger can exceeds the set temperature, scale clogging occurs in the heat exchanger Can be grasped.

  In the case of clogged fins, it becomes difficult for the combustion gas to flow between the fins of the heat exchanger, the amount of combustion gas recovered in the heat exchanger decreases, and the combustion gas is exhausted while maintaining a high temperature. The temperature of the vessel does not rise, and the surface temperature of the heat exchanger can body does not rise. On the other hand, in the case of scale clogging, the temperature of the heat exchanger rises due to the combustion gas, but since the heat cannot be transferred efficiently to the water flowing through the heat exchanger tubes, the temperature of the heat exchanger itself rises abnormally. As a result, the surface temperature of the heat exchanger can body also rises abnormally.

  That is, by directly measuring the surface temperature of the heat exchanger can body by the temperature detection means, and detecting an abnormal temperature rise of the heat exchanger can body that occurs due to the heat transfer of the heat exchanger being hindered by scale clogging, Since it is possible to distinguish between scale clogging and fin clogging, compared to the method of judging by the rise in hot water temperature after stopping combustion or change in heat exchange efficiency during combustion operation, even during combustion operation Scale clogging can be accurately determined. Moreover, when determining scale clogging, it is possible to prevent fluctuations in the amount of hot water supply and the temperature of hot water supply against the intention of the user.

And since the temperature detection means is provided on the surface of the heat exchanger can body in the vicinity of the downstream side of the heat transfer tube closest to the combustion portion of the heat exchanger, immediately above the combustion portion that always burns during hot water supply operation, By detecting the abnormal temperature rise of the heat exchanger can body by the temperature detection means provided near the place where the possibility of scale clogging of the heat transfer tube is high, the scale clogging can be grasped reliably and quickly. be able to.

  In addition, temperature detection means is provided at the above-mentioned locations of the heat exchanger can body, and scale clogging is determined using the surface temperature of the heat exchanger can body, so it is easy to determine scale clogging even during combustion operation. It can be applied to the combustion operation with the minimum combustion amount of the burner unit, can be applied to instant hot water, and can be applied to a large capacity hot water supply device.

It is a schematic block diagram of the hot water supply apparatus which concerns on the Example of this invention. It is a front view of a hot water supply apparatus. It is a longitudinal cross-sectional view of the lower side from the heat exchanger part of a hot water supply apparatus. It is a top view of the lower stage heat exchange area | region of a heat exchanger part. It is a flowchart of scale clogging determination operation control.

  Hereinafter, modes for carrying out the present invention will be described based on examples.

First, the whole structure of the hot water supply device 1 of the present invention will be described.
As shown in FIGS. 1 to 4, the hot water supply device 1 is applied as a heat source device such as a hot water supply device or a heating device, and burns fuel gas to use water contained in the combustion gas or water. It constitutes a gas water heater that heats hot water.

  That is, the hot water supply device 1 includes a blower fan 2 for supplying combustion air, a burner unit 3 for burning fuel gas, a heat exchanger unit 4 for exchanging heat between the combustion gas and water by the burner unit 3, An exhaust pipe 5 for discharging the exhaust gas after heat exchange by the heat exchanger section 4, various pipes such as a water inlet pipe 6a and a hot water outlet pipe 6b, and a control unit 7 for driving and controlling various devices are provided.

  The burner unit 3 includes a burner unit 11 that mixes and burns fuel gas supplied from a fuel supply pipe (not shown) and combustion air supplied from the blower fan 2, and a burner can containing the burner unit 11. A body 12 and a combustion space 13 above the burner unit 11 in the burner can body 12 are provided. The burner can body 12 is configured in a rectangular parallelepiped shape having an upper opening. A blower fan 2 is provided at the lower end of the burner can body 12.

  The burner unit 11 includes ten combustion pipes 14 arranged in parallel in the left-right direction, and is configured in a multistage system including a plurality of (for example, three) combustion stages 11a to 11c (FIGS. 1 and 1). 2, see FIG. Each of the combustion stages 11a to 11c includes, for example, five, two, and three combustion pipes 14, respectively, and is connected to a corresponding fuel supply pipe. Each of the combustion stages 11a to 11c can be independently controlled by the control unit 7, and the number of stages of the combustion stages 11a to 11c and the output thereof are adjusted according to various operations.

  During the hot water supply operation, for example, a one-stage combustion stage in which only the two combustion tubes 14 in the central combustion stage 11b are combusted, and a two-stage combustion stage in which the five combustion tubes 14 in the center and right combustion stages 11b and 11c are combusted. The four-stage combustion stage includes the three-stage combustion stage for burning the seven combustion tubes 14 of the left and center combustion stages 11a and 11b, and the four-stage combustion stage for burning the ten combustion pipes 14 of all the combustion stages 11a to 11c. The combustion operation is performed by switching the combustion stage. The central combustion stage 11b corresponds to a combustion section that is always combusted during a hot water supply operation.

  As shown in FIGS. 2 and 3, an igniter 15 and a frame rod 16 are respectively arranged in the combustion space 13 above the combustion stage 11 b of the burner unit 11. The igniter 15 and the frame rod 16 are respectively attached to the right side portion (portion corresponding to the combustion stage 11b) of the center portion of the front side plate 12a of the burner can body 12 in the left-right direction. The frame rod 16 is attached adjacent to the right side of the igniter 15.

  The igniter 15 generates an ignition spark with an ignition target provided in the burner unit 11, thereby generating a flame in the fuel-air mixture ejected from the burner unit 11. It is attached so that it may protrude to diagonally downward.

  The flame rod 16 applies an alternating voltage between the flames generated in the burner unit 11, and detects the direct current flowing from the flame rod 16 to the flame by using the conductivity and rectification action due to the ionization of the flame. It is for detecting the presence or absence of a flame, and is attached so as to protrude into the combustion space 13 and extend straight.

  As shown in FIGS. 1 to 4, the heat exchanger section 4 includes a heat exchanger 21 that recovers the heat of the combustion gas, a heat exchanger can body 22 that accommodates the heat exchanger 21, and the like. An exhaust tube 5 having an exhaust port 5a opened forward is provided at the upper end of the heat exchanger can body 22. The heat exchanger can body 22 is configured in a rectangular frame shape in plan view. The lower end portion of the heat exchanger can body 22 and the upper end portion of the burner can body 12 are joined by caulking or screw fastening. A thermal fuse 23 is provided around the heat exchanger can body 22 (see FIGS. 2 and 3).

  The heat exchanger 21 constitutes a fin-and-tube heat exchanger including a heat transfer tube 25 and a plurality of fins 26 and the like fixed to the heat transfer tube 25 so as to transfer heat. The heat transfer tubes 25 and the fins 26 are made of copper, but are not particularly limited to this material, and may be made of stainless steel.

  As shown in FIGS. 1 and 3, in the heat exchanger can body 22, the heat exchanger 21 includes an upper heat exchange region 21 </ b> A connected to the lower end of the exhaust pipe 5 (downstream side of the combustion gas flow) and the upper heat exchange region 21 </ b> A. , A two-stage structure including a lower heat exchange region 21B connected to the upper end of the combustion space 13 (the upstream side of the combustion gas flow).

  The heat transfer tube 25 includes a plurality of straight tube portions 27 arranged in parallel over two stages, and a plurality of connection tube portions 28 that connect ends of the plurality of straight tube portions 27. . Four straight pipe portions 27 are arranged in the upper heat exchange area 21A, and four straight pipe portions 27 are arranged in the lower heat exchange area 21B, and the upper heat exchange area 21A and the lower heat exchange area In each of 21B, the heat exchanger tubes 25 are each configured in a meandering shape in plan view (see FIG. 4).

  The downstream end of the inlet pipe 6a is connected to the upstream (rear) straight pipe portion 27a of the lower heat exchange area 21B, and the downstream (front) straight pipe section 27b of the lower heat exchange area 21B is connected to the upper stage. The straight pipe portion 27c on the upstream side (front side) of the heat exchange region 21A is connected via the connecting pipe portion 28, and the straight pipe portion 27d on the downstream side (rear side) of the upper heat exchange region 21A is located upstream of the outlet pipe 6b. Connected to the side edge.

  In the hot water supply apparatus 1, the fuel gas is supplied to the burner unit 11 from the fuel supply pipe and the combustion air is supplied from the blower fan 2, and the fuel-air mixture in which the fuel gas and the air are mixed is burned to burn the combustion space. A flame is formed in 13, and the combustion heat (combustion gas) of this flame heats the water in the heat exchanger 21 through the combustion space 13, and then the exhaust is discharged from the exhaust port 5 a through the exhaust tube 5 to the outside. To be discharged.

  On the other hand, in the heat exchanger 21, when clean water is supplied from an external clean water source to the water intake pipe 6a, the clean water first flows through the heat transfer pipe 25 in the lower heat exchange region 21B of the heat exchanger 21. Next, it flows through the heat transfer pipe 25 in the upper heat exchange region 21A of the heat exchanger 21, and the hot water is heated in the heat exchanger 21 as described above to become hot water, and discharged from the hot water discharge pipe 6b to the outside.

Next, the temperature detection sensor 31 related to the present invention will be described.
As shown in FIGS. 2 and 3, the hot water supply device 1 includes a temperature detection sensor 31 (corresponding to temperature detection means) for detecting the surface temperature of the heat exchanger can body 22. The temperature detection sensor 31 is directly above the combustion stage 11b (combustion part) that always burns during the hot water supply operation, and in the vicinity of the downstream side of the heat transfer tube 25 in the lower heat exchange region 21B closest to the combustion stage 11b of the heat exchanger 21. Are provided on the surface of the heat exchanger can body 22.

  That is, the temperature detection sensor 31 is in the vicinity of the passage portion 32 immediately above the combustion stage 11b in the straight pipe portion 27b on the downstream side of the lower heat exchange region 21B (see FIG. 4), and the front plate 12a of the burner can body 12 Is provided on the surface of the front side plate 22a of the heat exchanger can body 22 located immediately above the mounting portion of the frame rod 16 (see FIGS. 2 and 3).

  The temperature detection sensor 31 is composed of a known temperature detection sensor including a thermocouple 31a and a pair of lead wires 31b extending from the thermocouple 31a, and is fixed by brazing or adhesive tape. The pair of lead wires 31 b is connected to the control unit 7, and a detection signal based on the surface temperature of the front plate 12 a of the heat exchanger can body 22 of the temperature detection sensor 31 is supplied to the control unit 7.

Next, the control unit 7 will be described.
As shown in FIGS. 1 and 2, the control unit 7 controls the hot water supply device 1 and is configured such that various sensors are electrically connected and receive detection signals from the various sensors. ing. The control unit 7 controls driving of the blower fan 2, the burner unit 11 and the like based on the hot water temperature set by the operation remote controller, the amount of hot water supplied to the hot water tap, and detection signals received from various sensors, and hot water supply operation Execute.

Next, the scale clogging determination operation control related to the present invention will be described.
The control unit 7 (corresponding to the determination means) is configured so that the heat transfer tube 25 of the heat exchanger 21 is detected when the detected temperature (surface temperature of the heat exchanger can body 22) detected by the temperature detecting sensor 31 is equal to or higher than the set temperature. It is possible to execute scale clogging determination operation control that determines that scale is accumulated in the inside.

  Next, scale clogging determination operation control automatically executed by the control unit 7 during the hot water supply operation of the hot water supply device 1 will be described based on the flowchart of FIG. In the figure, the symbol Si (i = 1, 2,...) Indicates each step. A control program for the scale clogging determination operation control is stored in the control unit 7 in advance.

  In the flowchart of FIG. 5, when this control is started, first, in S <b> 1, the control unit 7 determines whether or not the hot water supply device 1 is in a hot water supply operation. That is, when the hot water supply apparatus 1 is in the hot water supply operation, that is, when the control unit 7 receives a signal based on the hot water supply operation, the determination of S1 is Yes, the process proceeds to S2, and the determination of S1 is No. Repeat S1.

  Next, in S2, the control unit 7 reads the detection signal of the temperature detection sensor 31, calculates the surface temperature of the front side plate 22a of the heat exchanger can body 22 based on this detection signal, and proceeds to S3.

  Next, in S3, it is determined whether or not the surface temperature of the heat exchanger can body 22 exceeds a set temperature (for example, about 180 to 200 degrees). If the surface temperature exceeds the set temperature, The determination is Yes, and the process proceeds to S4. If the surface temperature is equal to or lower than the set temperature, the determination in S3 is No, it is determined that the heat exchanger 21 is normal, and the process returns. The set temperature need not be limited to the above temperature, and can be changed as appropriate.

  Here, at the time of the hot water supply operation, as described above, the burner unit 11 is operated by adjusting the combustion stage in four stages according to the required heat quantity, but the two combustion pipes 14 in the central combustion stage 11b are Combustion operation is possible with the minimum combustion amount, and combustion is always performed during hot water supply operation.

  On the other hand, in the heat exchanger 21, the portion of the plurality of straight pipe portions 27 located directly above the combustion stage 11b in the lower heat exchange region 21B is constantly burned by the flames of the two combustion pipes 14 of the combustion stage 11b. Become. Moreover, since the clean water supplied to the heat transfer pipe 25 flows in a meandering manner from the upstream straight pipe portion 27a toward the downstream straight pipe portion 27b and is heated, the straight pipe is provided in the lower heat exchange region 21B. The hot water temperature of the part 27b rises most.

  For this reason, since the channel | path part 32 of the straight pipe part 27b of the some straight pipe parts 27 always burned with a flame may have the highest hot water temperature at the time of hot water supply operation, it is a scale compared with another part. Is easy to deposit. When scale clogging occurs in the passage portion 32 of the straight pipe portion 27b, the surface temperature of the heat exchanger can body 22 in the vicinity of the passage portion 32 becomes abnormal to about 180 to 200 degrees due to heat transfer failure of the heat exchanger 21. To rise. When the heat exchanger 21 is normal, the surface temperature of the heat exchanger can body 22 is normally maintained at about 120 ° C., so that scale clogging can be grasped by using this surface temperature.

  In the case of clogged fins, it becomes difficult for the combustion gas to flow between the fins 26 of the heat exchanger 21, the amount of heat of the combustion gas recovered by the heat exchanger 21 decreases, and the combustion gas is exhausted while maintaining a high temperature. Therefore, the temperature of the heat exchanger 21 does not rise, and the surface temperature of the heat exchanger can body 22 does not rise. On the other hand, in the case of scale clogging, the temperature of the heat exchanger 21 rises due to the combustion gas, but it cannot efficiently transfer heat to the water flowing through the heat transfer tube 25 of the heat exchanger 21, so the temperature of the heat exchanger 21 itself. Rises abnormally, and accordingly, the surface temperature of the heat exchanger can 22 also rises.

  Next, in S4, the control unit 7 determines that scale clogging has occurred in the heat exchanger 21, notifies the user of scale clogging via the display of the operation remote controller, voice, etc., and then returns. To do. After notifying scale clogging, the hot water supply operation may be continued, or immediately after the scale clogging is notified, the hot water supply operation may be stopped, or the scale clogging is notified and a predetermined time has elapsed. Operation may be stopped.

Next, the operation and effect of the hot water supply apparatus 1 of the present invention will be described.
The water heater 1 according to the present invention includes a temperature detection sensor 31 for detecting the surface temperature of the heat exchanger can 22 and heat exchange when the detected temperature detected by the temperature detection sensor 31 is equal to or higher than a set temperature. Since the control unit 7 for determining that the scale is accumulated in the heat transfer tube 25 of the heat exchanger 21 is provided, when the surface temperature of the heat exchanger can body 22 becomes equal to or higher than the set temperature, the heat exchanger 21 has a scale. It can be understood that clogging has occurred.

  That is, the surface temperature of the heat exchanger can body 22 is directly measured by the temperature detection sensor 31, and an abnormal temperature rise of the heat exchanger can body 22 generated due to the blockage of the heat exchanger 21 due to clogging of the scale is detected. By doing so, it is possible to distinguish between scale clogging and fin clogging, so compared to the method of judging by the rise in hot water temperature after combustion stop and change in heat exchange efficiency during combustion operation, Even so, scale clogging can be accurately determined. Moreover, when determining scale clogging, it is possible to prevent fluctuations in the amount of hot water supply and the temperature of hot water supply against the intention of the user.

  Further, the temperature detection sensor 31 is provided on the surface of the heat exchanger can body 22 in the vicinity of the downstream side of the heat transfer tube 25 that is immediately above the combustion portion that always burns during hot water supply operation and closest to the combustion portion of the heat exchanger 21. Therefore, the temperature clogging of the heat exchanger tube 22 is detected by the temperature detection sensor 31 provided in the vicinity of the portion where the possibility of the clogging of the heat transfer tube 25 is likely to occur. It is possible to grasp reliably and quickly.

  Furthermore, since the temperature detection sensor 31 is provided at the above-described portion of the heat exchanger can body 22 and the scale clogging is determined using the surface temperature of the heat exchanger can body 22, the scale clogging is also performed during the combustion operation. The determination can be easily performed, the combustion operation with the minimum combustion amount of the burner unit 11 can be handled, the hot water can be handled, and the hot water supply device with high capacity can also be handled.

Next, a mode in which the above embodiment is partially changed will be described.
[1] The temperature detection sensor 31 of the above embodiment is provided on the surface of the front plate 22a of the heat exchanger can body 22 in the vicinity of the passage portion 32 of the straight pipe portion 27b, but it is necessary to limit to this position. If it is in the vicinity of the passage where the hot water temperature is likely to rise most in the heat transfer tube 25, it can be changed as appropriate.

[2] The temperature detection sensor 31 of the above embodiment is mainly composed of a thermocouple 31a. However, the temperature detection sensor 31 is not limited to this structure, and may be composed of a thermistor or an infrared sensor. What was comprised by this may be employ | adopted and it can change suitably.

[3] The burner unit 11 of the above-described embodiment includes ten combustion pipes 14 and is configured in a multistage system including three combustion stages 11a to 11c. However, the present invention is not particularly limited to this structure. The number of combustion stages in the burner unit and the number of combustion tubes in each combustion stage can be changed as appropriate.

[4] In addition, those skilled in the art can implement the present invention by adding various modifications without departing from the spirit of the present invention, and the present invention includes such modifications. It is.

1 Water heater 7 Control unit (determination means)
21 heat exchanger 22 heat exchanger can body 25 heat transfer tube 31 temperature detection sensor (temperature detection means)

Claims (1)

In a hot water supply apparatus comprising a fin-and-tube heat exchanger for heating clean water with combustion gas, and a heat exchanger can body for housing the heat exchanger,
A temperature detection means for detecting the surface temperature of the heat exchanger can body, and a scale accumulates in the heat transfer tube of the heat exchanger when the detected temperature detected by the temperature detection means exceeds a set temperature. Determination means for determining that the
The temperature detecting means is provided on the surface of the heat exchanger can body in the vicinity of the downstream side of the heat transfer tube closest to the combustion portion of the heat exchanger, immediately above the combustion portion that always burns during hot water supply operation. A water heater characterized by that.